Algae are a diverse group of photosynthetic organisms that form a type of biomass that has attracted significant attention in recent years because of its ability to produce oil (hereinafter “algal oil”). Algal oil is rich in lipids and can be processed, e.g., via hydroprocessing and/or isomerization, to produce biofuels, such as bio-diesel, bio-jet, and the like.
Many of the extraction methods employed to extract oil from non-algae biomass feedstocks, such as vegetables, seeds, and the like, are non-disruptive type methods. These non-disruptive type methods generally do not disrupt the biomass cells and tend to produce relatively clean oils, e.g., vegetable oils, canola oil, sunflower oil, etc., with a substantial portion of the contaminants remaining behind in the biomass cells after the oil has been removed. Unfortunately, these non-disruptive type methods do not work well with algae because algae cells are relatively small, e.g., about 2 to about 20 nm, and have thick cell walls that make the extraction of algal oil more difficult.
Rather, algal oils are typically extracted from algae using disruptive type methods. Disruptive type methods include mechanical, thermal, enzymatic, or chemical methods that disrupt the algae cells to extract the algal oil as either a predominately lipid or esterified lipid oil or as liquefied algal biomass. However, by disrupting the algae cells, contaminants are readily removed from the algae cells together with the algal oil during extraction. These contaminants may include metals and phosphorus that are very problematic for downstream processing, such as processes for converting the algal oil to a biofuel. In particular, the metals and phosphorus contained in the algal oil are poisonous to many catalysts (e.g. hydroprocessing catalyst, isomerization catalyst, etc.) that are used to convert algal oils to biofuels. Unfortunately, current methods for removing contaminants from the algal oil prior to downstream oil conversion have proven to be unsatisfactory and currently limit the utilization of algal oils to produce biofuels.
Accordingly, it is desirable to provide methods for removing contaminants from algal oil to form a contaminant-depleted algal oil that may be further processed, for example, to produce a biofuel. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.